Google is your best friend. I see that you are connected with a Car Rental service in Van City. I would highly recommend you begin doing research on your competitor's inbound links and figure out which are high PR/high mR websites. You may want to focus more on the latter as PR seems pretty much dead and there hasn't been an update to publicly visible Google PR since December of last year. Atleast mozRank is updated on a fairly regular basis.

Well, like @Pixelatedkarma said Google is your best friend you can always use it to search forums, and what better for you would be is try to learn what your competitors are doing and the best way to do that would be sneaking onto your competitors backlinks look where you competitors is building its backlink from and I am sure you can also extract handful of good travel forums.

Thanks for your replies. Actually, i had analyzed my competitors site. But Dont know whether are using Forum posting or any other to gain inbound links. What are the ways to analyse them? Please help me to improve my site's PR.

You could use a free tool like opensiteexplorer. It should show you what links it sees on a site. There are many many other better tools for link analysis out there but the best ones I found personnally are some of the premium versions of downloadable tools. They will pull alot of links for you and then part of the fun is figuring out what each site is (forum, blog, etc.) and how they got the link.

well @ashleydaniel there are a number of tools available over the web which can help you with it, you can try using ahrefs tool it gives a better insight of your competitor backlinks. I am using the same to analayse competitors backlinks so you can try it out !